Storm water and septic systems have been in wide use for many years. Pre-molded Polyethylene galleries have also been utilized for leaching and drainage systems. The advantage to utilizing these galleries is that they are lightweight, easy and quick to install, and relatively inexpensive.
Most of the water used in households around the United States is employed to carry off wastes, the majority of these wastes being organic and inorganic solids. In cities, wastewater is often collected in a sewer system and carried away to central sewage treatment plants. However, in rural and often in suburban residential areas, individual septic systems are used to treat household waste.
Septic systems are utilized to process waste and wastewater so that the water can seep into the sub-soil of the surrounding ground. Typically septic systems are comprised of a cement septic tank buried in the ground along with a leaching field extending from the septic tank. Once the waste and wastewater is deposited in the septic tank, solid particles sink to the bottom and small light particles rise to the surface with liquid layer called effluent being located between.
The effluent exits the septic tank through a pipe by means of hydrostatic pressure in the tank. The effluent flows into an adjoining leaching or drain field where it is permitted to seep through the surrounding ground.
Pre-molded Polyethylene galleries have increasingly been utilized for leaching and drainage systems. Such a system is disclosed in U.S. Pat. No. 5,087,151 to DiTullio (“the '151 patent”) the disclosure of which is hereby incorporated by reference, which discloses a drainage and leaching field system comprising vacuum-molded polyethylene galleries that are designed to be connected and locked together in an end-to-end fashion. The '151 patent provides a lightweight, easy to install and structurally sound installation.
The galleries disclosed in the '151 patent comprise a single pre-molded polyethylene layer with an arch-shaped configuration having upstanding ribs running transverse to the length of the gallery. The ribs provide compressive strength to the gallery where, often it is desired to install the galleries under parking areas and under roadways. However, because the galleries are made of only a single layer the ribs form a corrugated and uneven surface on the interior walls of the galleries.
It is desirable to utilize the entire leaching field to distribute the effluent and particles that are deposited therein. However, most leaching fields are fed from one end and therefore the effluent and particles must travel the length of the connected galleries to be evenly distributed. Therefore, a build-up of particles can take place at the inlet end of the galleries, especially with the uneven surfaces forming pockets for particles to lodge in. In many cases, it is not feasible to feed the galleries from numerous points to achieve the desired distribution.
Galleries as disclosed in the '151 patent are also used to handle storm water runoff. Storm water drainage systems are usually separate from septic systems. In storm water drainage applications, the galleries are generally fed from one end and storm water is fed from gallery to gallery the length of the installation. During heavy rains, it is vital that the drainage system quickly take away the storm water that is deposited therein. The corrugated surface formed by the upstanding ribs on the interior walls of the galleries provide resistance to the flow of water thereby limiting the ability of the galleries to quickly process large quantities of storm water runoff in a limited time.
Therefore, what is desired is a leaching field utilizing pre-molded polyethylene galleries that facilitate the distribution of effluent and particles along its entire length.
It is also desired to provide a system utilizing pre-molded polyethylene galleries that present a low-friction surface on the interior walls for the quick removal of storm water runoff.